用于Oracle的MySQL等效会话变量

在MySQL中,我可以使用单个@创建一个访问会话变量.示例初始化:

set @myVar = true;

一些包含此代码的触发器:

if (@myVar is not true) then
  execute something

Oracle 10g中的等价物是什么？

SQL> EXEC DBMS_SESSION.SET_CONTEXT('CLIENTCONTEXT', 'myvar', 'myvalue');

PL/SQL procedure successfully completed

SQL> SELECT SYS_CONTEXT('CLIENTCONTEXT', 'myvar') FROM dual;

SYS_CONTEXT('CLIENTCONTEXT','M
--------------------------------------------------------------------------------
myvalue